1. Technical Field
The present invention relates generally to autonomous spacecraft control systems; and, specifically, it relates to onboard control systems which manage spacecraft operational systems, including performance monitoring and fault detection with adaptive fault recovery and performance optimization with little, if any, assistance from ground-based support.
2. Related Art
FIG. 1 is a schematic block diagram of a conventional spacecraftis interaction with ground based support. Particularly, a spacecraft 101 operates pursuant to sequences of low level commands (hereinafter "LLCs") received from remote ground support 103 via wireless transceivers 105 and 107. Ground support personnel work with monitoring and control systems 109 to formulate such LLC sequences to carry out a mission.
In most cases, to generate an LLC sequence, the personnel and the monitoring and control systems 109 must be aware of the current operating status of the spacecraft 101. Thus, a flight manager 111 is charged with continuously collecting data (hereinafter "monitoring data") received from pluralities of sensors 113 that monitor various spacecraft resources and hardware. The flight manager 111 must send the monitoring data and status information generated by the flight manager 111 to ground support 103. However, because of limitations in bandwidth, ground support 103 must direct the flight manager 111 to only send the portions of the available monitoring data and status information (together referred to hereinafter as idata streamsi) that currently seem most important.
As the data streams are received, the personnel and the monitoring and control systems 109 must analyze the data streams, and, if necessary, identify, modify or create LLC sequences for delivery to the spacecraft 101. The monitoring and control systems 109 transmit the LLC sequences to the spacecraft 101 where they are executed by a flight manager 111. The LLC sequences might, for example, direct the flight manager 111 to adjust one of actuators 115, disable or enable one of the sensors 113, and/or initiate operation of a payload processor 117 to manipulate a payload 119.
Additionally, through continuous monitoring and analysis of the spacecraft data streams, the ground support 103 attempts to determine the success or failure of LLC sequences executed by the flight manager 111. If, for example, an LLC sequence caused a misalignment of the spacecraft 101 as determined through monitoring and analyzing subsequent data streams received, the ground support 103 must attempt to generate a new LLC sequence (and possibly others thereafter) with hopes of achieving alignment.
Calculations needed to generate the LLC sequence become quite complex even for seemingly easy tasks due to changing spacecraft conditions. Such calculations typically involve an analysis of current spacecraft data streams to predict the future status of the spacecraft 101 (e.g., orientation, velocity, acceleration, hardware operations, etc.) when an LLC sequence will be executed. The LLC sequences must be constructed and/or adjusted based on the prediction. If the prediction proves incorrect (e.g., due to unexpected changes in spacecraft conditions or system performance), the desired impact of the LLC sequences is generally not achieved. Thereafter, corrective action must be taken in the form of further LLC sequences which again rely on further predictions of future spacecraft status, which may again prove incorrect. Communication propagation times, available bandwidth constraints and ground support and spacecraft processing times often exacerbate the problem.
Compounding matters, there is an ever increasing demand on spacecraft performance to meet mission goals requiring travel to many destinations over longer distances to perform greater numbers of more complex operations. Correspondingly, spacecraft designers are charged with the onerous tasks of meeting such demands while reducing costs and increasing reliability. As a result, using the structure and operation set forth in FIG. 1, designs for both general purpose (and sometimes reusable) spacecraft and corresponding general purpose ground support systems have been attempted. The general purpose spacecraft and ground support are supposed to accommodate a wide variety of anticipated or potential missions. To accommodate such general purpose design, overall system complexity has dramatically increased.
Thus, to accommodate conventional spacecraft, ground support systems require very complex and costly monitoring and control systems capable of receiving and rapidly processing large amounts of spacecraft data so that accurate identification, generation and/or modification to LLC sequences can be achieved. The ground support systems must also be able to identify and overcome anamolous trends, and rapidly identify, isolate and recover from both spacecraft and ground system faults. As a design goal, the control, adjustment and recovery of a spacecraft should be possible under all circumstances. As can be appreciated, with conventional designs, this goal is not easily met.